Power Assets minority investors are in a formidable position to get tycoon Li Ka-shing to up his offer

Hong Kong tycoon Li Ka-shing should be crying at his latest merger party.

Proxy advisers Institutional Shareholder Services and Glass Lewis have recommended in recent days that minority shareholders in Mr. Li’s Power Assetsvote down a merger with controlling shareholder Cheung Kong Infrastructure, or CKI. These advisers’ sway should force Mr. Li to change course and augment his offer for the second time. And if he decides instead to pull the deal, Power shareholders may still benefit.